Understanding the trophodynamics of Yellow Sea Ecosystem: the role of Euphausia pacifica

Abstract

Euphausia pacifica play a key role to transfer the energy to higher trophic level and maintain the function and structure of Yellow Sea ecosystem because of their abundance and high biomass. Although understanding their feeding ecology is one of key information to accurately elucidate the structure and the function of Yellow Sea ecosystem, very limited information is available on their feeding ecology and behavior through the season. Therefore, we collected specimens of E. pacifica and their potential preys (POM, size-fractioned zooplankton, etc.) from the selected stations (coastal vs. central region) in the southwest of Yellow Sea during April and August 2012. All samples were analyzed for carbon and nitrogen stable isotopes and dietary biomarkers (fatty acids) to track the source of energy and diet history of E. pacifica in Yellow Sea. According to the preliminary results, diets of E. pacifica were seasonally shifted from algal-based particles (i.e., diatom) to microbial-based particles (i.e., detritus, protozoa) as season progress. Also, carbon and nitrogen isotope values indicated that the carbon and nitrogen sources of E. pacifica and their potential preys were significantly different between coastal and central regions during the spring. Therefore, further analysis and in-situ feeding experiments could provide more detail information on temporal and spatial variation of the role of E. pacifica in Yellow Sea trophodynamics.